This invention relates to a dental apparatus having a plurality of instruments, holding means for said instruments, an extraction signal transmitter for each instrument operable to transmit an extraction signal when an instrument is extracted from its holding means, and a logic-actuation circuit for each instrument which is connected with the respective signal transmitter and also with the actuation circuits for the other instruments, each actuation circuit being operable to generate an actuation signal for the associated instrument and also to supply a blocking signal for the other actuation circuits when an extraction signal is transmitted from the associated signal transmitter and when no blocking signal from the other actuation circuits is present.
A dental apparatus of the above type is known from German Pat. specification No. 2 231 735. In the case of this known dental apparatus, the actuation circuits are connected with each other by a number of connecting lines which is equal to the number of instruments or actuating circuits. Each actuation circuit has a number of inputs equal to the number of instruments, one input being connected with the extraction signal transmitter and the remaining inputs with the connecting lines which transfer the blocking signal from the other actuation circuits. It is obvious that in the case of a relatively large number of instruments, with this design, a considerable outlay of components and space is necessary. Additionally, the outlay for assembly is considerable.